1. Technical Field
The invention relates to a toner for development of an electrostatic image, a method of producing the same, an electrostatic image developer, a toner cartridge, a process cartridge and an image forming apparatus.
2. Related Art
Generally in electrophotographic methods, a latent image is formed electrically by various means on the surface of a photoreceptor (latent image-holding member) that utilizes a photoconductive substance, and the formed latent image is developed with a toner to form a toner image, and thereafter this toner image is transferred onto the surface of a recording medium such as paper, if necessary via an intermediate transfer member. The transferred image is subjected to a fixing process such as heating, pressurizing, heat-pressurizing, such that an image is formed. Toner that remains on the surface of the photoreceptor is removed by various methods if necessary and utilized again in development of a toner image.
As a fixing technique for fixing a toner image that has been transferred onto the surface of a recording medium, a thermal roll fixing method wherein a recording medium material having a toner image transferred thereon is inserted between a pair of rolls composed of a heating roll and a pressure roll to fix the image is commonly used. As a similar technique, a technique in which one or both of the rolls is substituted with a belt is also known. In these techniques, an image that is fixed fast can be obtained at high speed and energy efficiency is high, because of direct contact with the image, as compared with other fixing methods.
With increased demand for saving the power required for image formation in recent years, techniques of lowering the fixing temperature of a toner in an attempt to save the electric power consumed in the fixing process, which consumes a certain proportion of the energy used in image formation and to expand the temperature range in which the toner can be fixed, are increasingly necessary. By lowering the toner fixing temperature, significant advantages are achieved including not only saving of electric power and expansion of the temperature range in which the toner can be fixed, but also reduction in a waiting time (warm-up time) required to increase the temperature of a member such as a fixing roll from room temperature to a fixable temperature, and achievement of longer operating life.
As a means of lowering the toner fixing temperature, a technique of lowering the glass transition temperature of a binder resin contained in the toner is generally carried out. However, when the glass transition temperature is made too low, powder aggregation (blocking) occurs easily, and thus it is important to satisfy both low-temperature fixability and prevention of blocking.